1. Field of the Invention
This invention relates to an assembly which comprises an injection mold of an injection molding machine, which mold comprises back plates, and coupling means for connecting supply lines to said mold for supplying temperature control fluids and for withdrawing such fluids from said mold, and for transmitting electric power and oil underpressure and/or compressed air for the performance of auxiliary operations in the mold, such as the hydraulic pulling of a core from said mold, an ejection of moldings from said mold by means of compressed air, and a delivery of control-signals. Said coupling means comprise a mold-side coupling part, which is secured to the movable mold section of the injection mold, and together with a machine-side coupling part is adapted to constitute a movable coupling for connecting supply lines to said mold, and another mold-side coupling part, which is secured to the stationary mold section of the injection mold and together with another machine-side coupling part is adapted to constitute a stationary coupling for connecting supply lines to said mold. The assembly also comprises hydraulic cylinders, which are operable in dependence on the program of a computer of the injection molding machine to couple each of said machine-side coupling parts to the associated mold-side coupling parts, wherein the closing stroke of the hydraulic cylinder comprises a coupling movement for coupling the machine-side coupling part to the mold-side coupling part.
2. Description of the Prior Art
In the operation of injection molding machines the injection mold must be preheated before the beginning of the molding operation to an optimum temperature for making the molding. That preheating will be described hereinafter as the temperature control of the injection mold and is effected in that a temperature control liquid is pumped through suitable temperature control passages of the body of the injection mold. For an automatic control by which the injection mold is maintained at a desired temperature, which depends on the optimum operating temperature, it is also necessary to supply electric power, e.g., for temperature sensors, to said mold. In most cases the temperature control is effected when the injection mold is in its operative position in the clamping region of the injection molding machine.
Certain auxiliary operations may have to be performed in the injection mold during the molding operation, e.g., when it is desired to make moldings having an intricate shape or moldings formed with internal or external screw threads. In such cases the surfaces defining the mold cavity often comprise surfaces of metal cores, with or without screw threadmolding portions. To permit the removal of the molding from the mold, the cores are pulled or unscrewed from the molding means of motor drives incorporated in the injection mold or by means of electric motors. Other auxiliary operations may also be required to be performed by means of compressed air, e.g., to blow the molding out of the mold. Said auxiliary operations to be performed in the injection mold may depend on a supply of oil under pressure and/or compressed air or of electric power in the form of electric signals for controlling or automatically controlling such auxiliary operating functions.
A known injection mold and coupling means assembly of the kind described hereinbefore is disclosed in DE 3228434 A1 and in the company publication "Netstal News No. 20 February 1986 Netstal-Machinery Ltd. 8752 Nafels, Switzerland. In that known assembly all supply lines are adapted to be coupled to and to be uncoupled from the injection mold when it is in its operative position in the clamping region of the injection molding machine. For that purpose, identical coupling part carriers for both mold sections provided, which carry the coupling parts for the temperature control and the coupling parts for the auxiliary operations. One coupling part carrier is secured to the back plate of the stationary mold section and another, identical coupling carrier is secured to the back plate of the movable mold section. Said mold-side coupling part carriers are associated and aligned with machine-side coupling part carriers, which are also identical to each other. In such an injection mold and coupling means assembly the couplings are substantially symmetrically arranged on the injection mold so that the manufacture is facilitated but the connections of the supply lines for the temperature control, on the one hand, and the connections of the supply lines for the auxiliary operations, on the other hand, cannot be made at spaced apart locations and at different times. Besides, a potential buyer can only decide to purchase the entire coupling means for the temperature control and for all auxiliary operations even when certain auxiliary operations will not be required. Such coupling means must be provided with a hydraulic cylinder for moving the coupling parts into engagement with each other and for locking the coupling parts in their engaged position and requires a large space.
Another known injection mold and coupling means assembly of the kind described first hereinbefore is disclosed in U.S. Pat. No. 4,710,121. In that assembly the supply lines for the temperature control are coupled to and uncoupled from the injection mold when the latter is held on a conditioning table outside the injection molding machine. When a new mold has been temperature controlled and is moved to the clamping region to replace a previously used mold, the coupling connections are maintained as well as during the transfer of a previously used mold from the clamping region of the machine to the conditioning table. The conditioning table is provided with machine-side identical coupling parts (see FIG. 7) which are disposed above the injection mold when it is in position on the conditioning table and said machine-side coupling parts are operatively connected to hydraulic cylinders for actuating said machine-side coupling parts. The machine-side coupling parts are guided during the closing movement of the hydraulic cylinder on vertical coupling pins, which are supported on a bridge provided on the conditioning table. For the movement of the injection mold provided with the supply lines from the conditioning table to the clamping region of the injection molding machine and in the opposite direction it is necessary to provide the machine-side supply lines with flexible and freely movable end sections. Additional couplings (as indicated 36 to 39 in FIGS. 1, 2, 4) are provided for auxiliary operations, said additional couplings are moved in a closed state by motive power of the injection mold when it is moved from the conditioning table into the clamping region. In such an arrangement it is inherently impossible to ensure that the coupling parts will be closed in a sufficiently concentric position. Besides, the motive power by which the mold is moved from the conditioning table to the clamping region is often not sufficient for effecting a reliable coupling. But the known assembly affords the great advantage that a new injection mold before it is used can be held on a conditioning table and can suitably be temperature-controlled to be at the molding temperature while the molding operation performed by the injection molding machine with the presently installed injection mold, which will subsequently be replaced, is still continued. As the temperature control of a new injection mold may often take more than one hour, the possibility just explained will substantially shorten the downtimes involved in an exchange of the molds.